21017889 has 6 divisors (see below), whose sum is σ = 30359186. Its totient is φ = 14011920.

The previous prime is 21017881. The next prime is 21017897. The reversal of 21017889 is 98871012.

It is an interprime number because it is at equal distance from previous prime (21017881) and next prime (21017897).

It can be written as a sum of positive squares in only one way, i.e., 12723489 + 8294400 = 3567^2 + 2880^2 .

It is not a de Polignac number, because 21017889 - 2³ = 21017881 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21017881) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1167652 + ... + 1167669.

Almost surely, 2^21017889 is an apocalyptic number.

It is an amenable number.

21017889 is a deficient number, since it is larger than the sum of its proper divisors (9341297).

21017889 is a wasteful number, since it uses less digits than its factorization.

21017889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2335327 (or 2335324 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 21017889 is about 4584.5271293777. The cubic root of 21017889 is about 275.9707357126.

The spelling of 21017889 in words is "twenty-one million, seventeen thousand, eight hundred eighty-nine".